Signal Canceller in the Carrier Super-positioning Satellite Networks

Abstract

To establish the interference canceller, generating replicas of unwanted carriers is a key. This paper addresses the design and performances of two types of signal canceller that are used for two typical types of satellite communications, namely P-MP VSAT (Point-to-Multi-Point Very Small-Aperture Terminal) and P-P (Point-to-Point) paired carrier systems. For P-MP VSAT, we show a simplified method where a replica of an unwanted carrier is generated by demodulating it. We have developed a reference simulator to simulate the behavior and performance. This simulator takes into account degradation due to implementation. The source code developed here is applicable to the implementation of FPGA. We also propose a method to generate replicas by stably measuring the satellite round-trip delay by multi-component code (MCC) on a real-time basis for P-P, since we cannot apply the same method to this case as we can for VSAT systems. We use MCC (Multi-component Code) to measure the delay as quickly and accurately as possible. It is the key how stably the acquisition of the code is established in the actual environment of satellite channel which is suffered from heavy noise and large level variation. We show a method to stabilize acquisition process of MCC by normalizing multilevel correlation using a level obtained by additional loop.